Hubble space telescope spies teenage galaxies

DEEP SPACE Ten thousand galaxies fill a tiny patch of sky in a new image from the Hubble Space Telescope. Ultraviolet light (blue) comes from star factories in galaxies that were active 5 to 10 billion years ago.

BOSTON — The distant universe just got a new dash of color. Ultraviolet images from the Hubble Space Telescope reveal star birth in galaxies that existed 5 billion to 10 billion years ago. The new images can help researchers reconstruct how galaxies grew to form the variety of shapes and sizes seen today.

There’s been a gap in astronomers’ understanding of galaxy growth, said Harry Teplitz on June 3 at the American Astronomical Society Meeting. The Caltech astrophysicist likened the gap to learning about people by watching only infants and college graduates. “We want to study galaxies in their teenage years,” he said.

The new images add ultraviolet data to the Hubble Ultra Deep Field, a well-studied region of the sky in the constellation Fornax. The region is one-tenth as wide as a full moon yet contains roughly 10,000 galaxies. Ultraviolet light lets astronomers see the youngest, hottest, most massive stars in distant galaxies and is the best tool researchers have for understanding star formation.

Hubble’s new images show stars forming in individual clumps spread throughout each galaxy. “We knew that was the case for galaxies today,” Teplitz said, “but no one had seen it in a teenage galaxy.”